Function encode 

pub fn encode(value: u64, buf: &mut [u8]) -> Result<usize, WireError>

Encode a u64 value as a QUIC-style VarInt into buf.

Returns the number of bytes written.

Errors

• WireError::BufferTooSmall if buf is not large enough.
• WireError::InvalidVarInt if value exceeds VARINT_MAX.